An electrical potential difference between two electrodes located on opposite surfaces of an elastomeric body generates an electric field leading to a force of attraction. As a result, the distance between the electrodes changes and the change leads to compression of the elastomeric material which is thereby deformed. Such structures can be used for making transducers for various purposes. When implemented as actuators they are sometimes referred to as “artificial muscles” due to certain similarities with a muscle. They can also be used as sensors for sensing strain, deflection, temperature variation, pressure etc., or they can be used as generators for converting mechanical energy to electrical, sometimes referred to as energy harvesting. Herein we will generally refer to these structures as transducers or polymer transducers.
U.S. Pat. No. 6,376,971 discloses a compliant electrode which is positioned in contact with a polymer in such a way, that when applying a potential difference across the electrodes, the electric field arising between the electrodes contracts the electrodes against each other, thereby deflecting the polymer.
Due to the deformation of the polymer, the electrodes move, and the connector which connects the electrode to a power source must constantly follow the movement of the electrode. Typically, the connector is made sufficiently long to avoid that the electrode constitutes a constraint for the free movement of the polymer and thus reduces the efficiency of the device. Evidently, the long connectors may get entangled or be in the way. Furthermore, fatigue may be experienced over time whereby the conductance of the connector is reduced or the connector may fail completely. Finally, it is generally difficult to provide an even distribution of an electrical field in a very thin electrode. Normally, the resistance in the electrode is high, and the resistance may increase depending on the degree of expansion of the polymer.
Additionally, traditional connectors are typically only attached to the electrode at an end point of the connector, i.e. at a single point of attachment, since otherwise the connector would again limit the movement of the electrode and thus the elastic deformation of the polymer. Due to this single-point attachment, it may be difficult to obtain an even distribution of the electrical field in the typically very thin electrodes.